Apparatus and methods for communicating control resource set data

ABSTRACT

A communication system is disclosed in which a communication device and a base station initially communicate using a first bandwidth. The communication device monitors for control data transmitted, by the base station, using a first control resource set conveyed in the first bandwidth. The communication device and the base station switch to using a second bandwidth, wherein the second bandwidth is different to the first bandwidth, and the communication device monitors for control data transmitted, by the base station, using a second control resource set that is conveyed in the second bandwidth.

TECHNICAL FIELD

The present invention relates to a communication system. The inventionhas particular but not exclusive relevance to wireless communicationsystems and devices thereof operating according to the 3rd GenerationPartnership Project (3GPP) standards or equivalents or derivativesthereof. The invention has particular although not exclusive relevanceto bandwidth adaptation in the so-called ‘Next Generation’ systems.

BACKGROUND ART

The latest developments of the 3GPP standards are referred to as theLong Term Evolution (LTE) of Evolved Packet Core (EPC) network andEvolved UMTS Terrestrial Radio Access Network (E-UTRAN), also commonlyreferred as ‘4G’. In addition, the term ‘5G’ and ‘new radio’ (NR) referto an evolving communication technology that is expected to support avariety of applications and services. Various details of 5G networks aredescribed in, for example, the ‘NGMN 5G White Paper’ V1.0 by the NextGeneration Mobile Networks (NGMN). 3GPP intends to support 5G by way ofthe so-called 3GPP Next Generation (NextGen) radio access network (RAN)and the 3GPP NextGen core network.

Under the 3GPP standards, a NodeB (or an ‘eNB’ in LTE, ‘gNB’ in 5G) isthe base station via which communication devices (user equipment or‘UE’) connect to a core network and communicate to other communicationdevices or remote servers. For simplicity, the present application willuse the term base station to refer to any such base stations and use theterm mobile device or UE to refer to any such communication device. Thecore network (e.g. the EPC in case of LTE) hosts functionality forsubscriber management, mobility management, charging, security, andcall/session management (amongst others), and provides connection forcommunication devices to external networks, such as the Internet.

Communication devices might be, for example, mobile communicationdevices such as mobile telephones, smartphones, user equipment, personaldigital assistants, laptop/tablet computers, web browsers, e-bookreaders and/or the like. Such mobile (or even generally stationary)devices are typically operated by a user, although it is also possibleto connect so-called ‘Internet of Things’ (IoT) devices and similarmachine-type communication (MTC) devices to the network. For simplicity,the present application refers to mobile devices (or UEs) in thedescription but it will be appreciated that the technology described canbe implemented on any communication devices (mobile and/or generallystationary) that can connect to a communications network forsending/receiving data, regardless of whether such communication devicesare controlled by human input or software instructions stored in memory.

In 3GPP networks, user data is transmitted between base stations and UEsover the so-called Physical Downlink Shared Channel (PDSCH)—althoughother channels may also be used (e.g. a broadcast channel). Theso-called Physical Downlink Control Channel (PDCCH)—which is normallyprovided within the same frequency band as the PDSCH—carries DownlinkControl Information (DCI) for UEs. The DCI specifies which UE is beingscheduled for transmission (over the PDSCH) and over which specificcommunication resources.

3GPP technical report (TR) 23.799 V0.7.0 describes a possiblearchitecture and general procedures for NextGen (5G) systems planned forRelease 14 of the 3GPP standards. 3GPP also studied the potential use offrequency bands up to 100 GHz for new (5G) radio access networks, with amaximum channel bandwidth of 400 MHz per NR carrier in Rel-15.Directional beamforming and massive antenna technologies may also beused in order to overcome the severe channel attenuation characteristicsassociated with certain high frequency bands (e.g. mmWave bands). Theterm ‘massive antenna’ refers to an antenna having a high number ofantenna elements (e.g. 100 or more) arranged in an array. Effectively,such a massive antenna may be used to communicate with several users atthe same time, thus facilitating multi-user multiple-input andmultiple-output (MU-MIMO) transmissions. A base station (also referredto as a transmission and reception point (TRP) in this case) may beconfigured to form respective beams for communicating with a pluralityof UEs substantially concurrently and using associated directionalbeams.

3GPP intends to provide one or more TRPs per new radio (NR) base station(i.e. 5G base station, or gNB). The expected NR control structure hasbeen presented in 3GPP Technical Report (TR) 38.802 V2.0.0, the contentsof which are incorporated herein by reference. This technical reportdescribes, amongst others, agreements regarding: a suitable mechanism torecover from beam failure; the possibility to apply radio frequency (RF)bandwidth adaptation; and motivation of bandwidth adaptation for NR.

In networks employing NR, up to hundreds or thousands of MHz systembandwidth may need to be supported on the air interface between basestations and user equipment. The motivation for bandwidth adaptation inNR networks has been summarised in 3GPP Tdoc R1-1611041. This documentdiscloses that in LTE, UEs consume over 60% of power for low-data-rateservices and decoding the PDCCH (which carries Downlink ControlInformation (DCI) for UEs). UE power consumption is substantiallyproportional to the operating bandwidth (the larger the bandwidth beingused, the larger the associated power consumption). Therefore, itappears to be more power efficient for UEs to adapt their operatingbandwidth to match their incoming (downlink) traffic.

SUMMARY OF INVENTION Technical Problem

3GPP agreed that NR-PDCCH transmissions will support robustness againstbeam pair link blocking and UEs can be configured to monitor NR-PDCCH ona number ‘M’ beam pair links simultaneously (whereM≥1,   [Math. 1]and the maximum value of M may depend at least on UE capability).However, it is still being studied whether to allow UEs to choose atleast one beam out of M beams for NR-PDCCH reception.

In NR, UEs can be configured to monitor NR-PDCCH on different beam pairlink(s) in different NR-PDCCH Orthogonal Frequency Division Multiplexing(OFDM) symbols. However, it is still being studied whether UEs shouldmonitor NR-PDCCH on one beam pair link with shorter duty cycle than onother beam pair link(s). The time granularity of configuration, e.g.slot level configuration, symbol level configuration is still not yetdecided. The configuration may also apply to scenarios where a UE maynot have multiple RF chains.

3GPP still needs to decide on the definition of monitoring NR-PDCCH onbeam pair link(s). It has been agreed that parameters related to UE Rx(receiver) beam setting for monitoring NR-PDCCH on multiple beam pairlinks are to be configured by higher layer signaling or MAC CE and/orconsidered in the search space design, although the required parametersand the need to support both higher layer signaling and MAC CE are stillunder study.

Regarding bandwidth adaptation, the following agreement was reached atthe 3GPP RAN1#86bis meeting: at least for single carrier operation, NRshould allow a UE to operate in a way where it receives at leastdownlink control information in a first RF bandwidth and where the UE isnot expected to receive in a second RF bandwidth that is larger than thefirst RF bandwidth within less than ‘X’ microseconds (the value of X isto be decided later).

It is for further study whether the first RF bandwidth is to be locatedwithin the second RF bandwidth, whether the first RF bandwidth is to beat the centre of the second RF bandwidth, the maximal ratio of the firstRF bandwidth over the second RF bandwidth, the detailed mechanism, andhow to implement RF bandwidth adaptation for RRM measurement.

3GPP also defined various control sets (sets of communication resourcesfor transmission of control data), although it is not yet specified howto support the larger bandwidth available in NR (e.g. compared to LTE)using such control resource sets. The inventors have also realised that,when multiple beams and appropriate bandwidth adaptation are used, itmay also be necessary to address the need for complexity reduction atthe UE (e.g. which may be monitoring multiple NR-PDCCHs).

Accordingly, preferred example embodiments of the present invention aimto provide methods and apparatus which address or at least partiallydeal with the above issues relating to bandwidth adaptation.

Although for efficiency of understanding for those of skill in the art,the invention will be described in detail in the context of a 3GPPsystem (5G networks), the principles of the invention can be applied toother systems.

Solution to Problem

In one aspect, the invention provides a method performed by acommunication device in a communication system comprising a base stationserving an associated communication area, the method comprising:communicating using a first bandwidth; monitoring for control datatransmitted, by the base station, using a first control resource setconveyed in the first bandwidth; switching to using a second bandwidthfor said communicating, wherein the second bandwidth is different to thefirst bandwidth; and monitoring for control data transmitted, by thebase station, using a second control resource set that is conveyed inthe second bandwidth.

The invention also provides a method performed by a communication devicein a communication system comprising a base station serving anassociated communication area formed by a plurality of directionalbeams, the method comprising: monitoring, in a first monitoringopportunity, for control data transmitted, by the base station, using afirst beam; monitoring, in a second monitoring opportunity, for controldata transmitted, by the base station, using a second beam; receivingcontrol data transmitted using at least one of: the first beam in thefirst monitoring opportunity; and the second beam in the secondmonitoring opportunity; and identifying a serving beam based onreception of the control data.

The invention also provides a method performed by a communication devicein a communication system comprising a base station serving anassociated communication area formed by a plurality of directionalbeams, the method comprising: receiving first control data transmitted,by the base station, using a first beam; receiving second control datatransmitted, by the base station, using a second beam; wherein saidsecond control data is a duplication of said first control data.

The invention also provides a method performed by a communication devicein a communication system comprising a base station serving anassociated communication area, the method comprising: communicatingusing a first bandwidth in accordance with a first discontinuousreception, DRX, configuration; switching to using a second bandwidth forsaid communicating, wherein the second bandwidth is different to thefirst bandwidth; and communicating using the second bandwidth inaccordance with a second DRX configuration; wherein the first DRXconfiguration represents a different DRX pattern to the second DRXconfiguration.

The invention also provides a method performed by a communication devicein a communication system comprising a base station serving anassociated communication area formed by a plurality of directional beamswherein each beam has an associated monitoring opportunity during whichthe base station may transmit control data, the method comprising:communicating in accordance with a discontinuous reception, DRX, patternhaving an on period and an off period; and monitoring for control datatransmitted, by the base station, using at least one beam in amonitoring opportunity associated with the at least one beam, based onthe DRX pattern; wherein the communication device monitors for controldata in the monitoring opportunity associated with the at least one beamduring the on period of the DRX pattern but does not monitor for controldata in the monitoring opportunity during the off period of the DRXpattern.

The invention also provides a method performed by a base station in acommunication system in which the base station serves a communicationarea, the method comprising: communicating with a communication deviceusing a first bandwidth; transmitting control data, to the communicationdevice, using a first control resource set conveyed in the firstbandwidth; switching to using a second bandwidth for said communicating,wherein the second bandwidth is different to the first bandwidth; andtransmitting control data, to the communication device, using a secondcontrol resource set that is conveyed in the second bandwidth.

The invention also provides a method performed by a base station in acommunication system in which the base station serves a communicationarea formed by a plurality of directional beams, the method comprising:monitoring, following transmission of control data using a first beam,for feedback from a communication device relating to the control datatransmitted using the first beam; monitoring, following transmission ofcontrol data using a second beam, for feedback from a communicationdevice relating to the control data transmitted using the second beam;receiving feedback from the communication device relating to at leastone of: the control data transmitted using the first beam; and thecontrol data transmitted using the second beam; and identifying aserving beam based on reception of the feedback.

The invention also provides a method performed by a base station in acommunication system wherein the base station serves an associatedcommunication area formed by a plurality of directional beams, themethod comprising: transmitting first control data, to at least onecommunication device, using a first beam; and transmitting secondcontrol data, to the at least one communication device, using a secondbeam; wherein said second control data is a duplication of said firstcontrol data.

The invention also provides a method performed by a base station in acommunication system in which the base station serves an associatedcommunication area, the method comprising: communicating, with acommunication device, using a first bandwidth in accordance with a firstdiscontinuous reception, DRX, configuration; switching to using a secondbandwidth for said communicating, wherein the second bandwidth isdifferent to the first bandwidth; and communicating, with thecommunication device, using the second bandwidth in accordance with asecond DRX configuration; wherein the first DRX configuration representsa different DRX pattern to the second DRX configuration.

The invention also provides a method performed by a base station in acommunication system in which the base station serves an associatedcommunication area formed by a plurality of directional beams whereineach beam has an associated monitoring opportunity during which the basestation may transmit control data, the method comprising: communicating,with a communication device, in accordance with a discontinuousreception, DRX, pattern having an on period and an off period; andtransmitting control data, to the communication device, using at leastone beam in a transmission opportunity associated with the at least onebeam, based on the DRX pattern, such that: control data is transmittedin the transmission opportunity associated with the at least one beamduring the on period of the DRX pattern but not transmitted in themonitoring opportunity during the off period of the DRX pattern.

Aspects of the invention extend to corresponding systems, apparatus, andcomputer program products such as computer readable storage media havinginstructions stored thereon which are operable to program a programmableprocessor to carry out a method as described in the aspects andpossibilities set out above or recited in the claims and/or to program asuitably adapted computer to provide the apparatus recited in any of theclaims.

Each feature disclosed in this specification (which term includes theclaims) and/or shown in the drawings may be incorporated in theinvention independently of (or in combination with) any other disclosedand/or illustrated features. In particular but without limitation thefeatures of any of the claims dependent from a particular independentclaim may be introduced into that independent claim in any combinationor individually.

Example embodiments of the invention will now be described, by way ofexample, with reference to the accompanying drawings in which:

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates schematically a cellular telecommunication system towhich example embodiments of the invention may be applied;

FIG. 2 is an overview of an exemplary bandwidth adaptation scenario inthe system shown in FIG. 1 ;

FIG. 3 is a block diagram of a mobile device forming part of the systemshown in FIG. 1 ;

FIG. 4 is a block diagram of a base station forming part of the systemshown in FIG. 1 ;

FIG. 5 illustrates schematically an exemplary way in which aggregatedcontrol resource sets may be provided in the system of FIG. 1 ;

FIG. 6 illustrates schematically an exemplary way in which aggregatedcontrol resource sets may be provided in the system of FIG. 1 ;

FIG. 7 illustrates schematically an exemplary way in which userequipment may monitor beams and select an appropriate beam in the systemof FIG. 1 ;

FIG. 8 illustrates schematically an example embodiment in whichdiscontinuous reception may be used for bandwidth adaptation; and

FIG. 9 illustrates schematically an example embodiment in whichdiscontinuous reception may be used for bandwidth adaptation.

DESCRIPTION OF EMBODIMENTS

Overview

FIG. 1 schematically illustrates a telecommunications network 1 (e.g. a3GPP NR network) in which user equipment 3 (mobile telephones and/orother mobile devices) can communicate with each other via base stations5 (denoted ‘gNB’) using an appropriate radio access technology (RAT). Itwill be appreciated that in 5G systems base stations are also referredto as transmit receive points (TRPs). As those skilled in the art willappreciate, whilst five mobile devices 3 and one base station 5 areshown in FIG. 1 for illustration purposes, the system, when implemented,will typically include other base stations and mobile devices.

Each base station 5 operates one or more associated cells either via aTRP located at the base station and/or one or more remotely located TRPs(not shown in FIG. 1 ). In this example, for simplicity, the basestation 5 operates a single cell. The base station 5 is connected to acore network 7 (e.g. via an appropriate gateway and/oruser-plane/control-plane function) and neighbouring base stations arealso connected to each other (either directly or via an appropriate basestation gateway). The core network 7 may include, amongst others, acontrol plane manager entity and a user plane manager entity, one ormore gateways (GWs) for providing a connection between the base stations5 and other networks (such as the Internet) and/or servers hostedoutside the core network.

The mobile device 3 connects to an appropriate cell (depending on itslocation and possibly on other factors, e.g. signal conditions,subscription data, capability, and/or the like) by establishing a radioresource control (RRC) connection with the base station 5 operating thatcell. The mobile device 3 and base stations 5 (and other transmissionpoints in the network) communicate over an appropriate air interfacewhich depends on the RAT used. The mobile devices 3 communicate withcore network nodes using so-called non-access stratum (NAS) signalling,which is relayed between the mobile device 3 and the appropriate corenetwork node by the base station 5/TRP serving the mobile device 3.

In this example, the base station 5 and the mobile devices 3 communicatewith each other using a multi-antenna scheme. Specifically, the basestation 5 operates an associated antenna array (e.g. a massive antenna)for providing a plurality of directional beams for communicating withthe various mobile devices 3 in the base station's 5 cell. Each beam isarranged to span (transmit) in a different direction (in threedimension, including elevation angle). Each beam may have an associatedidentifier (e.g. an appropriated ‘Beam ID’) which is unique (at leastwithin the cell).

In the network shown in FIG. 1 (and in NR networks in general), beammanagement can be seen as a set of appropriate (e.g. L1/L2) proceduresfor acquiring and maintaining a set of TRP(s) and/or UE beams that canbe used for downlink (DL) and uplink (UL) transmission/reception for aparticular mobile device 3. For example, beam management maybeneficially include one or more of the following aspects:

-   -   beam determination: for TRP(s) or UE to select its own Tx/Rx        beam(s);    -   beam measurement: for TRP(s) or UE to measure characteristics of        received beamformed signals;    -   beam reporting: for UE to report information of beamformed        signal(s) based on beam measurement; and    -   beam sweeping: operation of covering a spatial area, with beams        transmitted and/or received during a time interval in a        predetermined way.

The beam configuration used in the cell defines the number of beams andthe associated beam patterns. In the example shown in FIG. 1 , the totalnumber of beams is ‘N’, i.e. beams #1 though #N are currently configuredfor the cell of the base station 5 (‘N’ being a positive integer, atleast ‘1’).

The base station 5 is beneficially configured to transmit in its cell(or in each cell if the base station operates multiple cells) one ormore reference signals, for example, a set of beam-specific referencesignals (BRS). The mobile devices 3 may be configured to use theassociated reference signals for performing signal strength and channelestimate measurements for each beam (beam reporting). The measurementsare used (by the base station and/or the mobile device 3) forconfiguring an appropriate set of (one or multiple) beams for the mobiledevice 3, which set may be referred to as the operational beam set (OBS)of the mobile device 3.

The OBS may be dynamically updated, e.g. depending on signal conditions,load in the cell, a throughput and/or quality of service (QoS) requiredby the mobile device 3. Beneficially, when the OBS comprises multiplebeams, the likelihood of the mobile device 3 suffering a radio linkfailure (RLF)—i.e. a loss of connection with the base station 5—isgreatly reduced because in most situations there is at least onedirectional beam that the mobile device 3 can use and/or new beams maybe added to the OBS if needed (at least temporarily).

It will be appreciated that the bandwidth that a particular mobiledevice 3 is able to use in its communications with the base station 5(and other nodes via the base station 5) depends on the number of beamsincluded in its associated OBS. However, it will also be appreciatedthat the bandwidth allocated/available for the mobile device 3 withinany beam will not necessarily remain constant (i.e. the bandwidth in anybeam may depend on the throughput required for the services used by themobile device 3 and may also be (e.g. temporarily) affected by changesin signal conditions).

In this system, beneficially, the base station 5 is configured to adaptthe bandwidth allocated to the mobile device 3 in accordance with thecurrently applicable throughput requirements for the communications forthe mobile device 3 (which generally depend on e.g.services/applications being used by the mobile device 3 and/or itsuser). Specifically, the base station 5 is configured to control themobile device 3 to use a default (e.g. relatively low) bandwidth for itscommunications with the base station 5 unless the mobile device 3 (or anode in communication with the mobile device 3) requests a different(e.g. a relatively high) bandwidth for the mobile device 3. Suchrelatively high bandwidth may be referred to as a ‘wideband data pipe’and may be activated at least temporarily (e.g. as long as the increasedbandwidth is determined to be necessary and/or until expiry of anassociated timer).

The base station 5 may be configured to provide such (UE specific)wideband data pipe in a number of ways, including, for example:

-   -   by changing the bandwidth per beam (in at least one beam used by        the mobile device 3);    -   by changing the number of beams used by the mobile device 3        (add/remove beams to/from the OBS); and/or    -   by changing the DRX settings for the beams associated with the        mobile device 3.

It will be appreciated that bandwidth adaptation may be applied for themobile device 3 either temporarily (e.g. for a predetermined durationand/or until deactivation by the mobile device 3 or a network node) oras long as the mobile device 3 remains connected to the network 1.

FIG. 2 is an overview of an exemplary bandwidth adaptation scenario. Ascan be seen, bandwidth adaptation may be performed in dependence on the(changes in) data transmission needs of the mobile device 3. In thisexample, the mobile device 3 may be initially configured with arelatively small (e.g. a default) bandwidth (or ‘data pipe’), e.g. whenthe mobile device 3 is turned on or when it first accesses the networkor a particular beam/cell/base station. Alternatively, the mobile device3 may be configured with an appropriate bandwidth requested by themobile device 3 and/or a last used bandwidth.

The base station 5 is configured to transmit downlink control data 10(DCI via PDCCH and/or the like) regularly, e.g. in each subframe. Thedownlink control data 10 includes information identifying which mobiledevice 3 is being scheduled in that (or in a subsequent) subframe/slot,and the scheduled downlink data 12 is transmitted in accordance with theinformation included in the downlink control data 10. As can be seen,the bandwidth for the mobile device 3 at its initial access isrelatively narrow, therefore the downlink control data 10 is alsotransmitted using a narrow (the same) bandwidth. Beneficially,therefore, the mobile device's 3 power consumption associated withreceiving and decoding downlink control data 10 and any associateddownlink data 12 can be kept relatively low. Moreover, the base station5 is beneficially able to allocate its remaining resources to otherusers which may result in a better overall system efficiency.

When the mobile device 3 requires a larger bandwidth (e.g. due to anapplication on the mobile device 3 initiating data communication with aremote node, such as video streaming and/or the like), the base station5 is configured to adapt the associated bandwidth (data pipe)accordingly (at least temporarily). As can be seen, therefore, uponactivation of the wideband data pipe, the bandwidth available for thedownlink data 12 is increased (compared to its previous size) therebyallowing the mobile device 3 to communicate a larger amount of data ineach scheduling round (e.g. subframe). It will be appreciated that theassociated downlink control data 10 may also beneficially be transmittedover the increased bandwidth (although not necessarily over the entirewideband data pipe). Then, at the end of the mobile device's 3transmissions requiring the wider bandwidth, the wideband data pipeassociated with the mobile device 3 may be deactivated (or reconfiguredto an appropriate lower bandwidth, which might be different to theinitial bandwidth). The wideband data pipe may be deactivated eitherautomatically (e.g. when all data has been transmitted/received and/orupon expiry of an associated ‘activity’ timer) or when instructed by thebase station 5 (which may happen upon request by the mobile device 3).Beneficially, adaptation of the bandwidth allows the mobile device 3(and the base station 5) to operate more efficiently whilst stillallowing the mobile device 3 to use an appropriate wideband data pipewhen needed (e.g. temporarily).

There are a number of ways in which bandwidth adaptation may beperformed. For example, an appropriate (e.g. wider) bandwidth may beactivated/deactivated using one or more of the following methods.

In order to activate a larger bandwidth (than the current one), the basestation 5 may be configured to add appropriate signalling (e.g. 1-bit)to the DCI format in order to inform the mobile device 3 that it needsto open a wider bandwidth in the next possible slot (e.g. in the nextsubframe). The base station 5 may also apply cross-slot scheduling, inwhich case the base station 5 may be configured to schedule the mobiledevice 3 to use, in the next possible slot, a different bandwidth (e.g.larger than the current one). In other words, an indication to open alarger bandwidth may be sent by means of cross-slot scheduling. In orderto deactivate a wider bandwidth, an activity timer may be used (therebyavoiding the need for additional signalling). In this case, the mobiledevice 3 may be configured to go back to a smaller bandwidth (or itsprevious bandwidth) upon expiry of the activity timer (when apredetermined amount of time has passed after the mobile device's lastdata transmission requiring the current/wider bandwidth). It will beappreciated that the base station 5 may also be configured to use anappropriate Medium Access Control (MAC) control element (CE) forindicating of a wider (or different) bandwidth to the mobile device 3.

Beneficially, in order to facilitate bandwidth adaptation, a number ofpredefined control resource sets (e.g. sets of resources semi-staticallyconfigured—e.g. using RRC signalling—for the transmission of controldata) may be provided (e.g. to form an aggregated control resource setcomprising an aggregation of a plurality of smaller control resourcesets). In one example, at least a first (‘primary’) control resource setis provided (preferably having a narrow RF bandwidth), which comprisesan appropriate aggregation of control resource sets in the time domain.Such primary control resource set may be used by the mobile 3 as adefault or initial control resource set (or as a common search space)over which it expects to receive its control data and, optionally,associated user data (e.g. as long as the bandwidth meets the UE'srequirements). However, a second (‘secondary’) (preferably wider)control resource set may also be provided, which typically comprises anappropriate aggregation of control resource sets in the frequency domain(i.e. a wideband data pipe). Thus, when activation of a wideband datapipe is required for the mobile device 3, data may also be transmittedvia the resources corresponding to the secondary control resource setsas well (e.g. in addition to the primary control resource sets). It willbe appreciated that the primary and secondary control resource sets maybe provided via predetermined resources, known to both the mobile device3 and the base station 5. The control resource sets may be specific toeach UE, e.g. allocated based on information associated with the mobiledevice 3 and/or using a formula or function that results in differentcontrol resource sets for different UEs. Alternatively, the location ofthe primary and secondary control resource sets may be signalled to themobile device 3 explicitly.

Advantageously, in order to further optimise the complexity and powerconsumption of mobile devices 3, the base station 5 may be configured totransmit control data via a limited number of beams rather than allbeams allocated to a particular mobile device 3. For example, eachmobile device 3 may be configured to monitor control channels via anumber (e.g. two or three) of the best beams in a TDM manner. In anotherexample, the mobile devices 3 may be configured to monitor all theirassociated beams for control channel transmissions but only one beam ata time. In order to do so, appropriate monitoring occasions may beconfigured for each beam. Therefore, even if one of the beams (e.g. thecurrent serving beam) suffers from beam failure, the mobile device 3 isbeneficially able to receive its control data via a different beam (andsubsequently switch to that beam as its new serving beam) during anassociated monitoring occasion. In yet another example, control channeltransmissions for a particular mobile device 3 may be duplicated(transmitted simultaneously over two or more beams) effectivelyresulting in the control transmissions being super-positioned.

In a particularly beneficial example, the base station 5 and the mobiledevice 3 may be configured to apply a bandwidth adaptive DRX approach,in which the actual DRX setting being applied depends on the currentlyused bandwidth of the mobile device 3. For example, such ‘bandwidthadaptive’ DRX configuration may comprise a number of different DRXconfigurations (different DRX cycles and/or ON/OFF periods) fordifferent bandwidths that can be used by the mobile device 3. It will beappreciated that the DRX cycle may further be combined with the abovedescribed beam specific monitoring occasions. In this case, theeffective DRX ‘ON’ period may be derived as a combination of theapplicable beam scanning periods and the configured DRX pattern. Inother words, the mobile device 3 may be configured to monitor itsallocated beams (during respective associated beam monitoring occasionsper beam) only during ‘ON’ periods of its currently applicable DRXcycle.

As can be seen, therefore, appropriate bandwidth adaptation provides anumber of benefits such as flexibility in serving the mobile devices viathe base station's cell, improved power consumption (longer batterylife), and more efficient usage of the base station's communicationresources.

NR Overview

The following is a brief overview of NR (5G) networks and associatedterms.

It will be appreciated that multiple numerologies (subcarrier spacingand scaling factors) may be supported in NR systems. In the context ofNR technologies, a particular numerology is defined by its associatedsub-carrier spacing and cyclic prefix (CP) overhead. Multiple subcarrierspacings can be derived by scaling a basic subcarrier spacing by aninteger ‘N’. The numerology used can be selected independently of thefrequency band.

Physical resource block (PRB) is defined such that the number ofsubcarriers per PRB is the same for all numerologies (12 subcarriers perPRB).

Multiplexing different numerologies may be performed in time divisionmultiplexing (TDM) and/or frequency division multiplexing (FDM) mannerfor both downlink and uplink From UE perspective, multiplexing ofdifferent numerologies may be performed within/across a set of (one ormore) subframes.

For subcarrier spacing of 2^(m)×15 kHz, subcarriers are mapped on thesubset/superset of those for subcarrier spacing of 15 kHz in a nestedmanner in the frequency domain and the PRB grids are defined as thesubset/superset of the PRB grid for subcarrier spacing of 15 kHz in anested manner in the frequency domain.

From network perspective, multiplexing of transmissions with differentlatency and/or reliability requirements for enhanced Mobile Broadband(eMBB)/Ultra Reliable Low Latency Communications (URLLC) in downlink maybe supported by using the same subcarrier spacing with the same CPoverhead or using different subcarrier spacing. NR supports dynamicresource sharing between different latency and/or reliabilityrequirements for eMBB/URLLC in downlink Dynamic resource sharing betweenURLLC and eMBB may be supported by transmitting URLLC scheduled trafficwhere URLLC transmission may occur in resources scheduled for ongoingeMBB traffic. DL dynamic resources sharing between eMBB and URLLC isenabled without pre-emption by scheduling the eMBB and URLLC services onnon-overlapping time/frequency resources.

<Control Channel>

A number of control channels (e.g. NR-PDCCH) may be used for controllingcommunications between base stations and user equipment. It will beappreciated that, as in NR systems in general, at least the QPSKmodulation scheme is supported for the modulation of the NR-PDCCH. Forsingle stage downlink control information (DCI), the modulation schemefor NR-PDCCH is QPSK. In frequency-domain, the resource unit size (whichmay or may not include any demodulation reference signal (DM-RS)) for aparticular control channel may be a single PRB or multiple PRBs. It willbe appreciated that a NR-PDCCH candidate may consist of a set of NR-CCEsand a NR-CCE may consist of a fixed number of resource element groups(REGs). A REG may be one RB during one OFDM symbol (OS) which may or maynot include DM-RS (at least for the case where the DL control regionconsists of one or more OS(s) of a slot or a ‘mini-slot’). However, atleast for eMBB, multiple NR-CCEs cannot be transmitted on the same REGin one OFDM symbol except for spatial multiplexing to different UEs(MU-MIMO).

The so-called control resource set is defined as a set of REGs under agiven numerology. At least for single stage DCI design, each UE isconfigured to monitor for associated downlink control information in oneor more control resource sets (which may be specific to a particularUE). The BW for control resource set is smaller than or equal to thecarrier bandwidth (up to a certain limit). The control resource set is aset of REGs within which the UE attempts to blindly decode downlinkcontrol information. The REGs may or may not be frequency contiguous.When the control resource set spans multiple OFDM symbols, a controlchannel candidate may be mapped to multiple OFDM symbols or to a singleOFDM symbol. The gNB may be configured to inform UEs which controlchannel candidates are mapped to each subset of OFDM symbols in thecontrol resource set. This does not preclude that a UE may receiveadditional control information elsewhere within or outside the controlresource set in the same or different OFDM symbol(s). It will beappreciated that each UE may have one or more control resource sets. NRnetworks are expected to support dynamic reuse of at least part ofresources in the control resource sets for data (for the same or adifferent UE), at least in the frequency domain. From gNB perspective,DL control channel can be located at the first OFDM symbol(s) in a slotand/or mini-slot. UE-specific DL control information monitoringoccasions at least in time domain can be configured. It will beappreciated that a minimum granularity of DCI monitoring occasion may beconfigured (e.g. per UE). For example, the minimum granularity of DCImonitoring occasion may be once per slot (e.g. for single-stage DCIdesign).

<Beam Management>

In NR networks, a UE can trigger an appropriate mechanism to recoverfrom beam failure. The UE may be configured to trigger a mechanism torecover from beam failure when it has determined that beam failure hasoccurred. For example, the UE may determine that a beam failure eventhas occurred when the quality of beam pair link(s) of an associatedcontrol channel falls low enough (e.g. in comparison with a thresholdand/or at time-out of an associated timer) and/or meets any otherpredetermined condition. Whilst the beam pair link is used herein as anexample, it will be appreciated that other suitable measures may also beused. The network (gNB) configures the UEs with appropriate resourcesfor UL transmission of signals for recovery purpose. Configurations ofresources are supported where the base station is listening from all orpartial directions, for example, a random access region and/or the like.The UL transmission/resources to report beam failure may be located inthe same time instance as Physical Random Access Channel (PRACH) (e.g.resources orthogonal to PRACH resources) or at a time instance (whichmay be configurable per UE) different from PRACH. Transmission of DLsignal is supported for allowing the UE to monitor the beams foridentifying new potential beams.

NR supports beam management with and without beam-related indication.When beam-related indication is provided, information pertaining toUE-side beamforming/receiving procedure used for CSI-RS-basedmeasurement may be indicated through Quasi-Co-Location (QCL) to UE. NRsupports using the same or different beams on control channel and thecorresponding data channel transmissions.

For NR-PDCCH transmission supporting robustness against beam pair linkblocking, each UE may be configured to monitor NR-PDCCH on M beam pairlinks simultaneously, whereM≥1,   [Math. 2]and the maximum value of M may depend at least on UE capability. UEs maybe configured to monitor NR-PDCCH on different beam pair link(s) indifferent NR-PDCCH OFDM symbols. Parameters related to UE Rx beamsetting for monitoring NR-PDCCH on multiple beam pair links may beconfigured by higher layer signalling or MAC CE and/or considered in thesearch space design.

Mobile Device

FIG. 3 is a block diagram illustrating the main components of the mobiledevice 3 shown in FIG. 1 (e.g. a mobile telephone or other userequipment). As shown, the mobile device 3 has a transceiver circuit 31that is operable to transmit signals to and to receive signals from abase station 5 via one or more antenna 33. The mobile device 3 has acontroller 37 to control the operation of the mobile device 3. Thecontroller 37 is associated with a memory 39 and is coupled to thetransceiver circuit 31. Although not necessarily required for itsoperation, the mobile device 3 might of course have all the usualfunctionality of a conventional mobile telephone 3 (such as a userinterface 35) and this may be provided by any one or any combination ofhardware, software and firmware, as appropriate. Software may bepre-installed in the memory 39 and/or may be downloaded via thetelecommunications network or from a removable data storage device(RMD), for example.

The controller 37 is configured to control overall operation of themobile device 3 by, in this example, program instructions or softwareinstructions stored within the memory 39. As shown, these softwareinstructions include, among other things, an operating system 41, acommunications control module 43, a beam configuration module 44, abandwidth adaptation module 45, and a DRX module 46.

The communications control module 43 is operable to control thecommunication between the mobile device 3 and its serving basestation(s) 5 (and other communication devices connected to the basestation 5, such as further mobile devices and/or core network nodes).

The beam configuration module 44 is responsible for managing the beamsused (allocated for use) by the mobile device 3 in the current servingcell (or cells), e.g. by maintaining an appropriate OBS (or respectiveOBS's) for the mobile device 3. This includes, for example, adding andremoving cells (e.g. based on information provided by the base station 5and/or the signal measurement module 46) to the set of cells allocatedfor the mobile device 3.

The bandwidth adaptation module 45 is responsible for controllingswitching between appropriate bandwidths corresponding to the currentneeds (or configuration) of the mobile device 3. Specifically, thebandwidth adaptation module 45 controls activation/deactivation of anappropriate wideband data pipe. In some examples, this is achieved byswitching between using an appropriate primary control resource set andusing a secondary control resource set (e.g. in addition to the primarycontrol resource set).

The DRX module 46 is responsible for controlling the transceiver 31 fordiscontinuous reception (and/or transmission) when configured by thebase station 5. In some examples, such discontinuousreception/transmission may be employed per beam. In this case, bandwidthadaptation may be facilitated by changing the DRX pattern employed bythe mobile device 3.

Although not shown in FIG. 3 , it will be appreciated that the mobiledevice 3 may also include an appropriate measurement and reportingmodule for performing signal quality measurements and reporting (to thebase station 5). Such signal quality measurements may be performed over(beam specific) reference signals transmitted by the base station 5 andbased on an appropriate measurement configuration provided by theserving base station 5. The signal quality measurements may include, forexample, (detailed) Channel Status Information (CSI) measurements,reference signal received power (RSRP), reference signal receivedquality (RSRQ), received signal-to-noise ratio (SNR), and/or signal tointerference plus noise ratio (SINR) measurements and associatedreporting.

Base Station

FIG. 4 is a block diagram illustrating the main components of a basestation 5 shown in FIG. 1 . As shown, the base station 5 has atransceiver circuit 51 for transmitting signals to and for receivingsignals from the communication devices (such as mobile devices 3/userequipment) via one or more antenna 53 (e.g. an antenna array/massiveantenna), and a network interface 55 for transmitting signals to and forreceiving signals from network nodes (e.g. other base stations and/ornodes in the core network 7). The base station 5 has a controller 57 tocontrol the operation of the base station 5. The controller 57 isassociated with a memory 59. Software may be pre-installed in the memory59 and/or may be downloaded via the communications network 1 or from aremovable data storage device (RMD), for example. The controller 57 isconfigured to control the overall operation of the base station 5 by, inthis example, program instructions or software instructions storedwithin the memory 59. As shown, these software instructions include,among other things, an operating system 61, a communications controlmodule 63, a beam control module 64, a bandwidth adaptation module 65,and a DRX control module 66.

The communications control module 63 is operable to control thecommunication between the base station 5 and mobile devices 3 (userequipment) and other network entities that are connected to the basestation 5. The communications control module 63 also controls theseparate flows of downlink user traffic (via associated data radiobearers) and control data to be transmitted to communication devicesassociated with this base station 5 including, for example, control datafor core network services and/or mobility of the mobile device 3 (alsoincluding general (non-UE specific) system information and referencesignals).

The beam control module 64 is responsible for managing the beams used(allocated for use) by each mobile device 3 in the cell (or cells) ofthe base station 5, e.g. by maintaining an appropriate OBS (orrespective OBS's) for the mobile device 3. This includes, for example,adding and removing cells to the set of cells allocated for a particularmobile device 3 (e.g. based on information such as signal measurementsprovided by that mobile device 3, associated bandwidth requirements,services used, mobility of the mobile device 3, and/or other informationrelevant to the cell, such as load information).

The bandwidth adaptation module 65 is responsible for controllingswitching between appropriate bandwidths corresponding to the currentneeds (or configuration) of mobile devices 3 served by the base station5. Specifically, the bandwidth adaptation module 65 controlsactivation/deactivation of an appropriate wideband data pipe. In someexamples, this is achieved by switching between using an appropriate (UEspecific) primary control resource set and using a secondary controlresource set (e.g. in addition to the primary control resource set).

The DRX control module 66 is responsible for configuring mobile devices3 for discontinuous reception (and/or transmission) when appropriate. Insome examples, such discontinuous reception/transmission may be employedper beam. In this case, bandwidth adaptation may be facilitated bychanging the DRX pattern employed by the mobile device 3.

In the above description, the mobile device 3 and the base station 5 aredescribed for ease of understanding as having a number of discretemodules (such as the communications control modules and the bandwidthadaptation modules). Whilst these modules may be provided in this wayfor certain applications, for example where an existing system has beenmodified to implement the invention, in other applications, for examplein systems designed with the inventive features in mind from the outset,these modules may be built into the overall operating system or code andso these modules may not be discernible as discrete entities. Thesemodules may also be implemented in software, hardware, firmware or a mixof these.

Operation

A more detailed description will now be given (with reference to FIGS. 5to 9 ) of some ways in which bandwidth adaptation may be performed forcommunications between user equipment and TRPs (base stations).

FIGS. 5 and 6 illustrate schematically some exemplary ways in whichcontrol resource sets may be provided in the system of FIG. 1 .Specifically, FIG. 5 shows an example in which each PDSCH resource 71has the same number (e.g. one) of associated control resource sets 72(which may or may not be aggregated) and FIG. 6 shows various ways inwhich (UE specific) aggregated control resource sets 72 may be provided.

Such control resource sets 72 may be beneficially configured for aparticular mobile device 3 in order to allow the mobile device 3 toadapt its bandwidth to its current needs (e.g. to increase thebandwidth, at least temporarily).

Each control resource set 72 is a set of PRBs (‘X’ PRBs in FIG. 5 ) inthe frequency domain in which the mobile device 3 is configured toattempt to blindly decode its DCI (if present). In the time-domain, thenumber of OFDM symbols (OS) may be either fixed or variable (e.g. 1, 2,3 for a given UE). Each set of PRBs includes a predefined number ofcontrol channel elements (CCEs).

For initial access, the control resource sets 72 are preferablyconfigured in advance, for example, the mobile device 3 may obtain themfrom the master information block (MIB) or system information (broadcastby the base station 5) or derive them implicitly from initial accessinformation. Effectively, such pre-configured control resource sets 72represent a common search space (CSS) for a particular UE (or a group ofUEs). After initial access, further control resource sets 72 may beconfigured e.g. using higher layer signalling (RRC configuration and/orthe like) in a UE specific manner. Such additional control resource sets72 may be referred to as a UE-specific search space (USS).

The control resource sets 72 may be configured as either localised ordistributed transmission. In the localised case the control resourcesets 72 are substantially contiguous and in the distributed case thecontrol resource sets 72 are not contiguous (i.e. they are spacedapart). It is also possible that the control resource sets areoverlapping in frequency domain.

In the example shown in FIG. 5 , the control resource sets 72 (CSSand/or USS) are provided in the beginning of each DCI monitoringoccasion (e.g. over the first one or two OFDM symbols of each slot), ineach PDSCH portion 71. It will be appreciated that some or all controlresource sets 72 may be configured as common control resource sets (i.e.CSS), for example control resource set #3 in FIG. 5 . However, some orall control resource sets 72 may also be configured as UE specificcontrol resource sets (i.e. USS), if appropriate.

In this example, the mobile device 3 may be configured (limited) to use:only a pre-determined set of control resource sets 72 (e.g. one controlresource set) and the associated PDSCH portion(s) 71 by default; and alarger set (e.g. all control resource sets 72) and the associated (e.g.all) PDSCH portions 71 when its associated wideband data pipe is active.In other words, the base station 5 may employ appropriate bandwidthadaptation by changing the number of control resource sets 72 and/orPDSCH portions 71 allocated to the mobile device 3. Accordingly, thebase station 5 may beneficially configure the mobile device 3 tocommunicate using only its default (e.g. relatively narrow) bandwidthmost of the time, unless the mobile device 3 requires a relativelylarger bandwidth, in which case the base station 5 can allocate, atleast temporarily, additional control resource sets 72 (and additionalassociated PDSCH portions 71) for the mobile device 3.

It will be appreciated that the smaller or default set(s) of controlresource sets 72 may be referred to as primary control resource sets 72p and the additional set(s) of control resource sets 72 may be referredto as secondary control resource sets 72 s (for a given mobile device3).

In the example shown in FIG. 6 , similarly to FIG. 5 , the mobile device3 is initially configured to monitor a relatively smaller RF bandwidth(which may be applicable to the common search space and/or its UEspecific search space). In this example, bandwidth adaptation isrealised by changing the number and/or the aggregation of controlresource sets 72 (and/or associated PDSCH portions 71) employed for themobile device 3.

The mobile device 3 may be configured with aggregated (contiguous)control resource sets 72 in the time-domain (e.g. in a slot) in arelatively small RF bandwidth (herein referred to as its primary controlresource sets 72 p). Specifically, in the example shown in FIG. 6 ,three control resource sets 72 (control resource sets #1 to #3, eachcomprising two OFDM symbols) are assigned to the primary controlresource sets 72 p of the mobile device 3 (‘UE1’). It will beappreciated that the primary control resource sets 72 p may carry DCIfor that mobile device 3 and/or any associated user data (although userdata may also be scheduled for a different PDSCH region 71 and/or adifferent slot, i.e. outside the control resource sets 72 of the mobiledevice 3).

In this system, so-called secondary control resource sets 72 s may alsobe provided to compatible user equipment. Such secondary controlresource sets 72 s comprise further aggregated control resource sets 72within the frequency domain (although some of the secondary controlresource sets 72 s may also be provided in the time domain, ifappropriate). It will be appreciated that the secondary control resourcesets 72 s may be substantially contiguous although in the example shownin FIG. 6 they are non-contiguous. It is also possible that controlresource sets are overlapping in frequency domain.

When the mobile device 3 requires only a smaller RF bandwidth, itmonitors its primary control resource sets 71 p, and when it requires alarger RF bandwidth, the mobile device 3 also monitors its secondarycontrol resource sets 72 s.

Effectively, the mobile device 3 and the base station 5 are configuredto employ a two-dimensional control structure, in which the mobiledevice 3 is configured to monitor control resource sets 72 in thefrequency domain when operating in large RF bandwidth (when its widebanddata pipe is active) and monitor control resource sets 72 in the timedomain when operating in small RF bandwidth.

The bandwidth (denoted by ‘X’ in FIG. 6 ) of the smaller RF or primarycontrol resource sets 72 p may be beneficially defined in terms ofnumber of PRBs (for example 4, 6, 8, or 24 RBs) or it may be defined interms of MHz (for example 1.4 MHz, 5 MHz, 10 MHz, etc.). It will also beappreciated that the smaller RF bandwidth may be the same size as thebandwidth of the synchronisation signals (PSS and SSS) transmitted inthe cell of the base station 5. The primary and secondary controlresource sets 72 p, 72 s may be same or different for different UEs,e.g. in order to avoid blocking and/or to spread the control load in thefrequency domain.

Operation—Determining a Default Control Resource Set

It will be appreciated that, in practice, there may be many controlresource sets 72 in a given system bandwidth, but, each mobile device 3is assigned with its own respective primary control resource sets 72 pto monitor whilst operating in the small (default) RF bandwidth mode.

The following is a description of some exemplary ways in which a mobiledevice 3 can determine its (at least one) control resource set(s) 72included in the default control resource set 72 for that mobile device3.

Specifically, in a first example, the mobile device 3 is configured todetermine at least one (e.g. the first) control resource set (‘Set 1’)in the frequency domain associated with that mobile device 3, based oninformation identifying the mobile device 3 (e.g. an appropriate UEidentifier (UEID)). For example, if there are N control resource sets inthe system bandwidth, then the formula “UEID mod N” may be used (wherein‘UEID’ stands for an appropriate UE identifier associated with themobile device 3 for which the control resource set 72 is applicable).

In a second example, the mobile device 3 is configured to determine atleast one (e.g. the first) control resource set (‘Set 1’) associatedwith that mobile device 3, based on information explicitly signalled bythe network. In this case, the base station 5 may be configured totransmit, to each UE (or a group of UEs) in connected state, respectiveinformation identifying which control resource set 72 is to be used as astarting set for the primary control resource sets 72 p for that UE/UEgroup.

In a third example, the at least one (first) control resource set may bederived by the mobile device 3 implicitly, e.g. from initial accessinformation, for example, from an appropriate (e.g. one to one) mappingbetween each PRACH resource and the corresponding starting set 72 of theUE's primary control resource sets 72 p.

In a fourth example, the at least one (first) control resource set 72may be selected randomly (e.g. using a pseudo-random or hashingfunction). In this case, the selection of the starting control resourceset 72 is of equal probability between all control resource sets 72.This solution avoids the scenario of UEs selecting the same primarycontrol resource sets 72 p and therefore minimises collisions betweentransmissions for different UEs.

For example, the mobile device 3 and the base station 5 may beconfigured to use the following hashing function for deriving a startingcontrol resource set 72 in a given slot:Y _(k)=((A*Y _(k−1)) mod D) mod Nwhere Y−1=RNTI (Radio Network Temporary Identifier); A=39827; D=65537;N=the total number of control resource sets 72 in the system bandwidth(in a given cell), and k is a slot index (for example 0 . . . 19).

In each above example, the remaining control resource sets 72 (for agiven UE) may be fixed in the time domain (e.g. have a predeterminedlocation relative to the first control resource set) or they may beconfigurable (i.e. variable) by the base station 5.

The secondary control resource sets 72 s may also be implicitly derivedfrom the primary control resource sets 72 p (e.g. from the first setthereof), for example by applying a fixed offset relative to the primarycontrol resource sets 72 p or by applying odd or even resource sets 72in the frequency domain. It will also be appreciated that theappropriate secondary control resource sets 72 s may be explicitlysignalled from higher layers.

Operation—Complexity and Power Consumption Associated with BandwidthAdaptation

As explained above, NR networks employ a beam-oriented transmissiontechnique where the mobile device 3 is configured to monitor a NR-PDCCHon its serving beam for DCI transmissions. However, beam blocking mayhappen quite often (especially in the higher frequency bands employed inNR networks), therefore, NR compatible mobile devices 3 are capable ofmonitoring multiple beams for receiving NR-PDCCH.

Accordingly, each mobile device 3 may be configured to monitor multipleNR-PDCCHs (e.g. from N beams) even when it is using a relatively smallRF bandwidth (e.g. its associated primary control resource sets 72 p).

However, if the mobile device 3 monitors multiple NR-PDCCHs on multiplebeams, the processing complexity will increase (proportionally with thenumber of beams) for receiving and decoding the multiple NR-PDCCHs. Inother words, even when the wideband data pipe is deactivated, the mobiledevice 3 may be required to perform processing intensive monitoring ofmultiple beams and associated decoding (in order to determine whether aDCI is transmitted for that mobile device 3).

It is assumed by the inventors that the mobile device 3 may beconfigured to report appropriate feedback (to its serving base station5) about the best N beams (N depending on configuration), includingtheir associated CSI values (and/or the like). The base station 5receiving the feedback can thus assume that at least one beam isworking, but it does not know which one (due to potential beam blockingof one or more of the reported beams).

If the mobile device 3 is unable to successfully decode the controlchannels from all beams, then it is configured to declare a radio linkfailure (RLF) and initiate appropriate PRACH transmission procedures inorder to re-establish its connection with the base station 5.

Beneficially, in this system the mobile device 3 is configured tomonitor a small number of beams in a TDM manner (for example, the two orthree strongest beams or the best N beams which may be configured perUE, e.g. N=3 for UE1/N=2 for UE2). The mobile device 3 may be configuredto monitor these beams substantially continuously (but withoutmonitoring all beams associated with that mobile device 3). It will beappreciated that even in case of beam sweeping, beams are usuallytransmitted in a TDM manner, thus, it is still possible for the mobiledevice 3 to monitor the small number of beams as described above.Beneficially, since the mobile device 3 is not required to monitor alarge number (e.g. all) beams, it is possible to reduce its associatedcomplexity and power consumption.

It will be appreciated that the serving base station 5 can determinewhich beam has failed when it detects DTX feedback from the PDSCH 71scheduled on that beam. In this case, the mobile device 3 and the basestation 5 may replace the failed beam with the next suitable beam, whenappropriate.

<Monitoring Beams Periodically>

FIG. 7 illustrates schematically another exemplary way in which a mobiledevice 3 may monitor its associated beams.

In this example, rather than monitoring a limited (small) number ofbeams substantially continuously, the mobile device 3 is configured tomonitor each associated beam periodically, during respective beammonitoring occasions 75 (which are preferably different for each beam).For example, the mobile device 3 may be configured to monitor each beamin a round-robin manner and/or the like. The monitoring occasions 75 foreach beam should preferably be predefined (e.g. configured by theserving base station 5) in order for the base station 5 and the mobiledevice 3 to be aligned and avoid the mobile device 3 missing its DCItransmission.

In principle, the best beam for a particular mobile device 3 is theserving beam 76 that is used for scheduling data transmissions (controland user data) for that mobile device 3. In addition to the serving beam76, the mobile device 3 may also be required to monitor other beams forpotential beam switching (e.g. due to failure of the serving beam 76).

In this example, the base station 5 is configured to assume a possiblebeam failure with respect to a particular beam (serving beam 76) whenthe base station 5 does not receive any (explicit) Ack/Nack feedback(i.e. DTX) from the mobile device 3 following a PDSCH transmission onthat beam. When the base station 5 determines that there is a potentialbeam failure, it is configured to switch to another suitable beam andstart sending the control channel on that beam. Since the mobile device3 is configured to monitor each beam periodically, during respectivebeam monitoring occasions 75, it is likely to be able to receive thePDSCH (re)transmission on one of the other beams and confirm receipt ofthe transmission by generating and sending appropriate feedback. Themobile device 3, upon receiving the control channel in a new beam, isconfigured to switch to that beam as its new serving beam 76.

In the scenario illustrated in FIG. 7 , the mobile device 3 is initiallymonitoring beam #1 (its current serving beam 76) and also beams #2 and#3 in associated monitoring occasions 75. When the mobile device 3detects a control channel transmission (e.g. DCI) on its current servingbeam 76, it is configured to look for downlink transmissions via theserving beam 76 (and/or any other beam specified via the DCI). However,when the mobile device 3 detects a control channel transmission (e.g.DCI) on a different beam (in this example, beam #3), it is configured toswitch to that beam as its new serving beam 76 (as long as it remains asuitable beam for that mobile device 3 and/or until it is configuredotherwise).

<Duplicating PDCCH Transmission>

In yet another example, the base station 5 may be configured toduplicate its NR-PDCCH transmissions in each beam (N beams) so that themobile device 3 is able to see a super-positioned version of theNR-PDCCH (similarly to single frequency network (SFN) transmissions).

In order to achieve SFN type transmission, all involved beams need to becoordinated, and the transmission should preferably have the sameinitialisations. The SFN transmission can be applied to all slots or canbe applied to a subset of slots where during respective beam monitoringoccasions 75 the mobile device 3 and the base station 5 are both awareand aligned. Beneficially, this alternative may be used even when CSIfeedback is not available.

Operation—DRX

FIGS. 8 and 9 illustrate schematically some example embodiments in whichdiscontinuous reception/transmission may be used for bandwidthadaptation.

FIG. 8 illustrates an exemplary DRX approach, similar to DRX in LTE,albeit slightly tailored to bandwidth adaptation purposes. Effectively,in this case, the base station 5 configures the mobile device 3 withbandwidth adaptation dependent DRX settings or ‘bandwidth adaptive’ DRXconfiguration, which may comprise different DRX configurations(different DRX cycles and/or ON/OFF periods) for different bandwidthsused by the mobile device 3.

As can be seen, when the mobile device 3 operates in its smaller RFbandwidth region, for example at initial access, it applies a first DRXsetting in which an associated DRX ‘OFF’ time period is applied for arelatively short period (during which the mobile device 3 is configuredto turn off its transceiver 31) followed by a relatively longer ‘ON’time period (during which the mobile device 3 is configured to turn onits transceiver 31). Accordingly, the mobile device 3 can be configuredto monitor its associated beams only during the DRX ON window (in thegiven DRX cycle) which may result in further reduction in the mobiledevice's overall power consumption.

However, when operating in its larger RF bandwidth (with its widebanddata pipe being activated), the mobile device 3 is configured to employa different DRX setting. Specifically, in this example, a bandwidthadaptation specific DRX cycle may be provided such that an associatedDRX ‘OFF’ time period is applied for a relatively long period and a DRX‘ON’ time period is applied for a relatively short period (compared tothe OFF time period and/or the ON time period of the DRX cycle appliedduring small RF operation). Accordingly, even when operating over arelatively large bandwidth, the mobile device 3 may be able to keep itspower consumption at an optimal level due to applying a relatively shortDRX ON window (in the given DRX cycle).

In other words, the DRX setting applied by the mobile device 3 isdependent on the current RF bandwidth allocation (wideband data pipebeing activated or deactivated) for the mobile device 3. Beneficially,therefore, when the base station 5 configured an appropriate DRX settingfor the mobile device 3, it takes into account any frequency domaininformation/RF bandwidth that the mobile device 3 may use. Thus, a firstDRX setting may be provided for a default/initial/narrowband RFoperation and a second (different) DRX setting may be provided to themobile device 3 (either in advance or upon activation of the widebanddata pipe) for wideband RF operation.

Although in FIG. 8 the first and second DRX cycles have the sameduration, it will be appreciated that in some cases they may havedifferent durations, if appropriate. It will also be appreciated thatmore than two DRX settings may be provided, for example, different DRXsettings for different (ranges of) bandwidths, each DRX setting beingtailored to allow optimal power consumption at the mobile device 3 for aspecific bandwidth being used (e.g. falling within a range of bandwidthsassociated with that DRX setting). Since the base station 5 also knowswhich bandwidth is currently allocated for the mobile device 3 at anygiven time, the base station 5 is able to apply the correct DRX settingfor the mobile device 3 (and time its transmissions for that mobiledevice 3 to coincide with its associated ‘ON’ period based on thecurrently applicable DRX setting).

FIG. 9 illustrates a modification of the example shown in FIG. 8 . Inthis example, the mobile device 3 is configured to monitor multiplebeams, one by one, based on an associated beam scanning period having atime window during which the mobile device 3 is configured to monitor aparticular beam (and during which the mobile device may be configurednot to monitor other beams). As can be seen in the top three patterns ofFIG. 9 , each beam can have a different beam monitoring window withinits associated beam scanning period (which are repeated). Effectively,this corresponds to the embodiment described with reference to FIG. 7above, in which different beams have different associated beammonitoring occasions 75.

However, in this example, the mobile device 3 is also configured toemploy an appropriate DRX configuration (e.g. a bandwidth adaptive DRXconfiguration as described above with reference to FIG. 8 ).Beneficially, in this example the actual or effective DRX ‘ON’ periodmay be derived as a combination of the beam scanning period and theconfigured DRX pattern. Specifically, the mobile device 3 may beconfigured to monitor its allocated beams, during respective associatedbeam monitoring occasions 75 (or windows), only during ‘ON’ periods ofits currently applicable DRX cycle. Thus, in the example shown in FIG. 9, if the mobile device 3 is monitoring beams #1 and #3 only, then theresulting beam monitoring activity after applying the DRX cycle isillustrated by the bottom pattern.

A further benefit associated with this modification is that the mobiledevice 3 may be able to achieve further reduction in its overall powerconsumption whilst still being able to adapt its bandwidth and use anappropriate wideband data pipe when necessary.

Modifications and Alternatives

Detailed example embodiments have been described above. As those skilledin the art will appreciate, a number of modifications and alternativescan be made to the above embodiments whilst still benefiting from theinventions embodied therein. By way of illustration only a number ofthese alternatives and modifications will now be described.

It will be appreciated that the beam configuration may be different fordifferent cells, depending on the coverage/throughput requirements for aparticular cell. For example, a high number of very narrow beams may beused for a large cell radius, whilst fewer and relatively wider beamsmay be used to facilitate fast cell acquisition and reduce the overheadfor transmission of beam-specific reference signals. In some cases, thebeam configuration may consist of a single beam, defining the coverageof the whole cell (similarly to legacy cells).

It will also be appreciated that the beam configuration of a given cellmay change semi-statically, e.g. for the purposes of self-organisingnetwork (SON) adaptation such as Capacity and Coverage Optimisation(CCOpt) and/or the like. In this case, reconfiguration of a particularbeam configuration may include changing the beam-width of one or morebeams and/or changing the number of beams (e.g. switching beams on oroff).

In the above example embodiments, bandwidth adaptation is performed independence on the (changes in) data transmission needs of the mobiledevice. However, it will be appreciated that bandwidth adaptation may beperformed in dependence on a number of other factors as well, includingbut not limited to: system load; signal quality, modulation scheme,application/service being used (user activated and/or backgroundapplications/services); user subscription; UE capability, UE powerpreference; UE battery saving preference/battery level; UE mobility(stationary/mobile/pedestrian/high speed); user location(home/office/public area/commuting); network/base station/cell beingused; roaming/non-roaming users; time of day; and/or the like.

It will be appreciated that the specific bandwidth adaptation methodemployed and/or the way control resource sets are provided may differfrom cell to cell, from base station to base station, from UE to UE. Itwill also be appreciated that bandwidth adaptation may be providedselectively, for example, for a subset of the UEs being served by thebase station and/or a subset of beams employed by the base station.

In the above example embodiments the base station is described totransmit a plurality of directional beams. It will be appreciated thatdata may be transmitted substantially concurrently via the plurality ofbeams. However, in some cases, for example when a hybrid (part analogueand part digital) beamforming is used, it may not be possible totransmit all beams at once. It will be appreciated that in this case atechnique referred to as ‘beam sweeping’ (i.e. transmitting one beam ata time) may be used.

In the above example embodiments, the base station uses a 3GPP radiocommunications (radio access) technology to communicate with the mobiledevice. However, any other radio communications technology (i.e., WLAN,WI-FI®, WIMAX®, BLUETOOTH®, etc.) can be used between the base stationand the mobile device in accordance with the above embodiments. Theabove example embodiments are also applicable to ‘non-mobile’ orgenerally stationary user equipment.

In the above description, the mobile device and the base station aredescribed for ease of understanding as having a number of discretefunctional components or modules. Whilst these modules may be providedin this way for certain applications, for example where an existingsystem has been modified to implement the invention, in otherapplications, for example in systems designed with the inventivefeatures in mind from the outset, these modules may be built into theoverall operating system or code and so these modules may not bediscernible as discrete entities.

In the above example embodiments, a number of software modules weredescribed. As those skilled in the art will appreciate, the softwaremodules may be provided in compiled or un-compiled form and may besupplied to the base station or to the mobile device as a signal over acomputer network, or on a recording medium. Further, the functionalityperformed by part or all of this software may be performed using one ormore dedicated hardware circuits. However, the use of software modulesis preferred as it facilitates the updating of the base station or themobile device in order to update their functionalities.

Each controller may comprise any suitable form of processing circuitryincluding (but not limited to), for example: one or more hardwareimplemented computer processors; microprocessors; central processingunits (CPUs); arithmetic logic units (ALUs); input/output (IO) circuits;internal memories/caches (program and/or data); processing registers;communication buses (e.g. control, data and/or address buses); directmemory access (DMA) functions; hardware or software implementedcounters, pointers and/or timers; and/or the like.

The first control resource set may be specific to the communicationdevice (e.g. a UE-specific search space, USS). Alternatively, the firstcontrol resource set may be shared among a plurality of communicationdevices (e.g. a common search space, CSS). The second control resourceset may be specific to the communication device (e.g. a UE-specificsearch space, USS).

The first bandwidth may be smaller than the second bandwidth. The firstcontrol resource set may be provided across a first set of one or moretime domain resources (e.g. slots) and the second control resource setmay be provided across a second set of one or more time domain resources(e.g. slots), and the extent of the first set in the time domain may bedifferent to (e.g. larger than) the extent of the second set in the timedomain.

The first bandwidth may correspond to at least one of: a band defined interms of a number of resource blocks (e.g. 4, 6, 8, or 24 resourceblocks); a band defined in terms of frequency (1.4 MHz, 5 MHz, or 10MHz); a band defined in terms of a bandwidth of a synchronisation signaltransmitted by the base station.

The at least one of the monitoring for control data transmitted usingthe first control resource set and the monitoring for control datatransmitted using a second control resource set may comprise monitoringfor control data (e.g. downlink control information, DCI) that specifieswhether the communication device is being scheduled for communicationsin a current transmission opportunity.

The method may further comprise: receiving control data transmittedusing at least one of said first and second control resource set whenmonitoring for that control data; and communicating (e.g. sending and/orreceiving) user data based on the received control data (e.g. over aPhysical Downlink Shared Channel, PDSCH) using a bandwidth substantiallyequal to the first or second bandwidth in which the control data wastransmitted.

The first control resource set may comprise an aggregation of aplurality of smaller control resource sets in the time domain. Thesecond control resource set may comprise an aggregation of a pluralityof control resource sets in the frequency domain (and optionally in thetime domain).

The method may further comprise identifying the first control resourceset prior to said monitoring for control data transmitted using thefirst control resource set.

The identifying of the first control resource set may be based oninformation associated with the communication device (e.g. using theformula ‘UEID mod N’, wherein ‘N’ represents the total number of controlresource set in a system bandwidth of the base station and ‘UEID’represents the information associated with the communication device).

The identifying of the first control resource set may be based on atleast one physical random access channel (PRACH) resource associatedwith the communication device.

The identifying of the first control resource set may be based on apseudo-random or hashing function.

The method may further comprise identifying the second control resource,prior to said monitoring for control data transmitted using the secondcontrol resource set, based on the first control resource set.

The first and second monitoring opportunities may occur at differentperiods in the time domain.

The first bandwidth may be small relative to the second bandwidth andthe first DRX configuration may represent a DRX pattern having an onperiod that is long relative to the second DRX configuration (and/or thefirst DRX configuration may represent a DRX pattern having an off periodthat is short relative to the second DRX configuration).

The communication device may be configured not to monitor for controldata in the monitoring opportunity associated with at least one otherbeam, during the on period of the DRX pattern.

The method may further comprise communicating (e.g. sending and/orreceiving) user data based on the transmitted control data (e.g. over aPhysical Downlink Shared Channel, PDSCH) using a bandwidth substantiallyequal to the first or second bandwidth in which the control data wastransmitted.

The base station may comprise a base station of a next generation(NextGen or 5G) radio access network.

Various other modifications will be apparent to those skilled in the artand will not be described in further detail here.

The whole or part of the example embodiments disclosed above can bedescribed as, but not limited to, the following supplementary notes.

(Supplementary Note 1)

A method performed by a communication device in a communication systemcomprising a base station serving an associated communication area, themethod comprising:

-   -   communicating using a first bandwidth;    -   monitoring for control data transmitted, by the base station,        using a first control resource set conveyed in the first        bandwidth;    -   switching to using a second bandwidth for said communicating,        wherein the second bandwidth is different to the first        bandwidth; and    -   monitoring for control data transmitted, by the base station,        using a second control resource set that is conveyed in the        second bandwidth.

(Supplementary Note 2)

The method according to Supplementary note 1, wherein the first controlresource set is specific to the communication device (e.g. a UE-specificsearch space, USS).

(Supplementary Note 3)

The method according to Supplementary note 1, wherein the first controlresource set is shared among a plurality of communication devices (e.g.a common search space, CSS).

(Supplementary Note 4)

The method according to any one of Supplementary notes 1 to 3, whereinthe second control resource set is specific to the communication device(e.g. a UE-specific search space, USS).

(Supplementary Note 5)

The method according to any one of Supplementary note 1 to 4, whereinthe first bandwidth is smaller than the second bandwidth.

(Supplementary Note 6)

The method according to any one of Supplementary notes 1 to 5, whereinthe first control resource set is provided across a first set of one ormore time domain resources (e.g. slots) and the second control resourceset is provided across a second set of one or more time domain resources(e.g. slots), wherein the extent of the first set in the time domain isdifferent to (e.g. larger than) the extent of the second set in the timedomain.

(Supplementary Note 7)

The method according to any one of Supplementary notes 1 to 6, whereinthe first bandwidth corresponds to at least one of: a band defined interms of a number of resource blocks (e.g. 4, 6, 8, or 24 resourceblocks); a band defined in terms of frequency (1.4 MHz, 5 MHz, or 10MHz); a band defined in terms of a bandwidth of a synchronisation signaltransmitted by the base station.

(Supplementary Note 8)

The method according to any one of Supplementary notes 1 to 7, whereinat least one of: the monitoring for control data transmitted using thefirst control resource set; and the monitoring for control datatransmitted using a second control resource set; comprises monitoringfor control data (e.g. downlink control information, DCI) that specifieswhether the communication device is being scheduled for communicationsin a current transmission opportunity.

(Supplementary Note 9)

The method according to any one of Supplementary notes 1 to 8, furthercomprising: receiving control data transmitted using at least one ofsaid first and second control resource set when monitoring for thatcontrol data; and communicating (e.g. sending and/or receiving) userdata based on the received control data (e.g. over a Physical DownlinkShared Channel, PDSCH) using a bandwidth substantially equal to thefirst or second bandwidth in which the control data was transmitted.

(Supplementary Note 10)

The method according to any one of Supplementary notes 1 to 9, whereinthe first control resource set comprises an aggregation of a pluralityof smaller control resource sets in the time domain.

(Supplementary Note 11)

The method according to any one of Supplementary notes 1 to 10, whereinthe second control resource set comprises an aggregation of a pluralityof control resource sets in the frequency domain (and optionally in thetime domain).

(Supplementary Note 12)

The method according to any one of Supplementary notes 1 to 11, whereinthe communication area is formed by a plurality of directional beamseach covering a respective portion of the communication area.

(Supplementary Note 13)

The method according to any one of Supplementary notes 1 to 12, furthercomprising identifying the first control resource set prior to saidmonitoring for control data transmitted using the first control resourceset.

(Supplementary Note 14)

The method according to Supplementary note 13, wherein the identifyingof the first control resource set is based on information associatedwith the communication device (e.g. using the formula ‘UEID mod N’,wherein ‘N’ represents the total number of control resource set in asystem bandwidth of the base station and ‘UEID’ represents theinformation associated with the communication device).

(Supplementary Note 15)

The method according to Supplementary note 13, wherein the identifyingof the first control resource set is based on at least one physicalrandom access channel, PRACH, resource associated with the communicationdevice.

(Supplementary Note 16)

The method according to Supplementary note 13, wherein the identifyingof the first control resource set is based on a pseudo-random or hashingfunction.

(Supplementary Note 17)

The method according to any one of Supplementary notes 13 to 16, furthercomprising identifying the second control resource, prior to saidmonitoring for control data transmitted using the second controlresource set, based on the first control resource set.

(Supplementary Note 18)

A method performed by a communication device in a communication systemcomprising a base station serving an associated communication areaformed by a plurality of directional beams, the method comprising:

-   -   monitoring, in a first monitoring opportunity, for control data        transmitted, by the base station, using a first beam;    -   monitoring, in a second monitoring opportunity, for control data        transmitted, by the base station, using a second beam;    -   receiving control data transmitted using at least one of: the        first beam in the first monitoring opportunity; and the second        beam in the second monitoring opportunity; and    -   identifying a serving beam based on reception of the control        data.

(Supplementary Note 19)

The method according to Supplementary note 18, wherein the first andsecond monitoring opportunities occur at different periods in the timedomain.

(Supplementary Note 20)

A method performed by a communication device in a communication systemcomprising a base station serving an associated communication areaformed by a plurality of directional beams, the method comprising:

-   -   receiving first control data transmitted, by the base station,        using a first beam;    -   receiving second control data transmitted, by the base station,        using a second beam;    -   wherein said second control data is a duplication of said first        control data.

(Supplementary Note 21)

A method performed by a communication device in a communication systemcomprising a base station serving an associated communication area, themethod comprising:

-   -   communicating using a first bandwidth in accordance with a first        discontinuous reception, DRX, configuration;    -   switching to using a second bandwidth for said communicating,        wherein the second bandwidth is different to the first        bandwidth; and    -   communicating using the second bandwidth in accordance with a        second DRX configuration;    -   wherein the first DRX configuration represents a different DRX        pattern to the second DRX configuration.

(Supplementary Note 22)

The method according to Supplementary note 21, wherein the firstbandwidth is small relative to the second bandwidth and the first DRXconfiguration represents a DRX pattern having an on period that is longrelative to the second DRX configuration (and/or the first DRXconfiguration represents a DRX pattern having an off period that isshort relative to the second DRX configuration).

(Supplementary Note 23)

A method performed by a communication device in a communication systemcomprising a base station serving an associated communication areaformed by a plurality of directional beams wherein each beam has anassociated monitoring opportunity during which the base station maytransmit control data, the method comprising:

-   -   communicating in accordance with a discontinuous reception, DRX,        pattern having an on period and an off period; and    -   monitoring for control data transmitted, by the base station,        using at least one beam in a monitoring opportunity associated        with the at least one beam, based on the DRX pattern;    -   wherein the communication device monitors for control data in        the monitoring opportunity associated with the at least one beam        during the on period of the DRX pattern but does not monitor for        control data in the monitoring opportunity during the off period        of the DRX pattern.

(Supplementary Note 24)

The method according to Supplementary note 23, wherein, during the onperiod of the DRX pattern, the communication device does not monitor forcontrol data in the monitoring opportunity associated with at least oneother beam.

(Supplementary Note 25)

A method performed by a base station in a communication system in whichthe base station serves a communication area, the method comprising:

-   -   communicating with a communication device using a first        bandwidth;    -   transmitting control data, to the communication device, using a        first control resource set conveyed in the first bandwidth;    -   switching to using a second bandwidth for said communicating,        wherein the second bandwidth is different to the first        bandwidth; and    -   transmitting control data, to the communication device, using a        second control resource set that is conveyed in the second        bandwidth.

(Supplementary Note 26)

The method according to Supplementary note 25, wherein the first controlresource set is provided across a first set of one or more time domainresources (e.g. slots) and the second control resource set is providedacross a second set of one or more time domain resources (e.g. slots),wherein the extent of the first set in the time domain is different to(e.g. larger than) the extent of the second set in the time domain.

(Supplementary Note 27)

The method according to Supplementary note 25 or 26, further comprisingcommunicating (e.g. sending and/or receiving) user data based on thetransmitted control data (e.g. over a Physical Downlink Shared Channel,PDSCH) using a bandwidth substantially equal to the first or secondbandwidth in which the control data was transmitted.

(Supplementary Note 28)

The method according to any one of Supplementary notes 25 to 27, whereinthe first control resource set comprises an aggregation of a pluralityof smaller control resource sets in the time domain.

(Supplementary Note 29)

The method according to any one of Supplementary notes 25 to 28, whereinthe second control resource set comprises an aggregation of a pluralityof control resource sets in the frequency domain (and optionally in thetime domain).

(Supplementary Note 30)

The method according to any one of Supplementary notes 25 to 29, furthercomprising identifying the first control resource set prior to saidtransmitting the control data using the first control resource set.

(Supplementary Note 31)

The method according to any one of Supplementary note 25 to 30, whereinthe base station comprises a base station of a next generation, NextGen,radio access network.

(Supplementary Note 32)

A method performed by a base station in a communication system in whichthe base station serves a communication area formed by a plurality ofdirectional beams, the method comprising:

-   -   monitoring, following transmission of control data using a first        beam, for feedback from a communication device relating to the        control data transmitted using the first beam;    -   monitoring, following transmission of control data using a        second beam, for feedback from a communication device relating        to the control data transmitted using the second beam;    -   receiving feedback from the communication device relating to at        least one of: the control data transmitted using the first beam;        and the control data transmitted using the second beam; and    -   identifying a serving beam based on reception of the feedback.

(Supplementary Note 33)

The method according to Supplementary note 32, wherein the transmissionof control data using a first beam and the transmission of control datausing a second beam occur at different periods in the time domain.

(Supplementary Note 34)

A method performed by a base station in a communication system whereinthe base station serves an associated communication area formed by aplurality of directional beams, the method comprising:

-   -   transmitting first control data, to at least one communication        device, using a first beam; and    -   transmitting second control data, to the at least one        communication device, using a second beam;    -   wherein said second control data is a duplication of said first        control data.

(Supplementary Note 35)

A method performed by a base station in a communication system in whichthe base station serves an associated communication area, the methodcomprising:

-   -   communicating, with a communication device, using a first        bandwidth in accordance with a first discontinuous reception,        DRX, configuration;    -   switching to using a second bandwidth for said communicating,        wherein the second bandwidth is different to the first        bandwidth; and    -   communicating, with the communication device, using the second        bandwidth in accordance with a second DRX configuration;    -   wherein the first DRX configuration represents a different DRX        pattern to the second DRX configuration.

(Supplementary Note 36)

The method according to Supplementary note 35, wherein the firstbandwidth is small relative to the second bandwidth and the first DRXconfiguration represents a DRX pattern having an on period that is longrelative to the second DRX configuration (and/or the first DRXconfiguration represents a DRX pattern having an off period that isshort relative to the second DRX configuration).

(Supplementary Note 37)

A method performed by a base station in a communication system in whichthe base station serves an associated communication area formed by aplurality of directional beams wherein each beam has an associatedmonitoring opportunity during which the base station may transmitcontrol data, the method comprising:

-   -   communicating, with a communication device, in accordance with a        discontinuous reception, DRX, pattern having an on period and an        off period; and    -   transmitting control data, to the communication device, using at        least one beam in a transmission opportunity associated with the        at least one beam, based on the DRX pattern, such that:    -   control data is transmitted in the transmission opportunity        associated with the at least one beam during the on period of        the DRX pattern but not transmitted in the monitoring        opportunity during the off period of the DRX pattern.

(Supplementary Note 38)

A communication device for a communication system comprising a basestation serving a communication area formed by a plurality ofdirectional beams, wherein the communication device comprises:

-   -   a controller and a transceiver;    -   wherein the transceiver is operable to communicate with the base        station using a first bandwidth; and    -   wherein the controller is operable to:        -   monitor for control data transmitted, by the base station,            using a first control resource set conveyed in the first            bandwidth;        -   switch the transceiver to using a second bandwidth for said            communicating, wherein the second bandwidth is different to            the first bandwidth; and        -   monitor for control data transmitted, by the base station,            using a second control resource set that is conveyed in the            second bandwidth.

(Supplementary Note 39)

A communication device for a communication system comprising a basestation serving a communication area formed by a plurality ofdirectional beams, wherein the communication device comprises:

-   -   a controller and a transceiver;    -   wherein the controller is operable to:        -   monitor, in a first monitoring opportunity, for control data            transmitted, by the base station, using a first beam;        -   monitor, in a second monitoring opportunity, for control            data transmitted, by the base station, using a second beam;    -   wherein the transceiver is operable to receive control data        transmitted using at least one of: the first beam in the first        monitoring opportunity; and the second beam in the second        monitoring opportunity; and    -   wherein the controller is operable to identify a serving beam        based on reception of the control data.

(Supplementary Note 40)

A communication device for a communication system comprising a basestation serving a communication area formed by a plurality ofdirectional beams, wherein the communication device comprises:

-   -   a controller and a transceiver, wherein the transceiver is        operable to:        -   receive first control data transmitted, by the base station,            using a first beam; and        -   receive second control data transmitted, by the base            station, using a second beam;    -   wherein said second control data is a duplication of said first        control data.

(Supplementary Note 41)

A communication device for a communication system comprising a basestation serving a communication area, wherein the communication devicecomprises:

-   -   a controller and a transceiver;    -   wherein the transceiver is operable to communicate using a first        bandwidth in accordance with a first discontinuous reception,        DRX, configuration;    -   wherein the controller is operable to switch the transceiver to        using a second bandwidth for said communicating, wherein the        second bandwidth is different to the first bandwidth; and    -   wherein the transceiver is operable to communicate using the        second bandwidth in accordance with a second DRX configuration;    -   wherein the first DRX configuration represents a different DRX        pattern to the second DRX configuration.

(Supplementary Note 42)

A communication device for a communication system comprising a basestation serving an associated communication area formed by a pluralityof directional beams wherein each beam has an associated monitoringopportunity during which the base station may transmit control data, thecommunication device comprising:

-   -   a controller and a transceiver;    -   wherein the controller is operable to:        -   control the transceiver to communicate in accordance with a            discontinuous reception, DRX, pattern having an on period            and an off period; and        -   monitor for control data transmitted, by the base station,            using at least one beam in a monitoring opportunity            associated with the at least one beam, based on the DRX            pattern; and    -   wherein the controller is operable to monitor for control data        in the monitoring opportunity associated with the at least one        beam during the on period of the DRX pattern but the controller        is operable to not monitor for control data in the monitoring        opportunity during the off period of the DRX pattern.

(Supplementary Note 43)

A base station for a communication system in which the base stationserves a communication area, wherein the base station comprises:

-   -   a controller and a transceiver;    -   wherein the transceiver is operable to:        -   communicate with a communication device using a first            bandwidth; and        -   transmit control data, to the communication device, using a            first control resource set conveyed in the first bandwidth;    -   wherein the controller is operable to switch the transceiver to        using a second bandwidth for said communicating, wherein the        second bandwidth is different to the first bandwidth; and    -   wherein the transceiver is operable to transmit control data, to        the communication device, using a second control resource set        that is conveyed in the second bandwidth.

(Supplementary Note 44)

A base station for a communication system in which the base stationserves a communication area formed by a plurality of directional beams,wherein the base station comprises:

-   -   a controller and a transceiver;    -   wherein the controller is operable to:        -   monitor, following transmission of control data using a            first beam, for feedback from a communication device            relating to the control data transmitted using the first            beam;        -   monitor, following transmission of control data using a            second beam, for feedback from a communication device            relating to the control data transmitted using the second            beam;    -   wherein the transceiver is operable to receive feedback from the        communication device relating to at least one of: the control        data transmitted using the first beam; and the control data        transmitted using the second beam; and    -   wherein the controller is operable to identify a serving beam        based on reception of the feedback.

(Supplementary Note 45)

A base station for a communication system in which the base stationserves a communication area formed by a plurality of directional beams,wherein the base station comprises:

-   -   a controller and a transceiver;    -   wherein the transceiver is operable to:    -   transmit first control data, to at least one communication        device, using a first beam; and    -   transmit second control data, to the at least one communication        device, using a second beam;    -   wherein said second control data is a duplication of said first        control data.

(Supplementary Note 46)

A base station for a communication system in which the base stationserves a communication area, wherein the base station comprises:

-   -   a controller and a transceiver;    -   wherein the transceiver is operable to communicate, with a        communication device, using a first bandwidth in accordance with        a first discontinuous reception, DRX, configuration;    -   wherein the controller is operable to switch the transceiver to        using a second bandwidth for said communicating, wherein the        second bandwidth is different to the first bandwidth; and    -   wherein the transceiver is operable to communicate, with the        communication device, using the second bandwidth in accordance        with a second DRX configuration;    -   wherein the first DRX configuration represents a different DRX        pattern to the second DRX configuration.

(Supplementary Note 47)

A system comprising the communication device according to any one ofSupplementary notes 38 to 42 and the base station according to any oneof Supplementary notes 43 to 46.

(Supplementary Note 48)

A computer implementable instructions product comprising computerimplementable instructions for causing a programmable communicationsdevice to become configured as the communication device according to anyone of Supplementary notes 38 to 42.

(Supplementary Note 49)

A computer implementable instructions product comprising computerimplementable instructions for causing a programmable communicationsdevice to become configured as the base station according to any one ofSupplementary notes 43 to 46.

This application is based upon and claims the benefit of priority fromUnited Kingdom patent application No. 1704762.2, filed on Mar. 24, 2017,the disclosures of which are incorporated herein in their entirety byreference.

The invention claimed is:
 1. A method performed by a user equipment (UE)for bandwidth adaptation for communication with a base station, themethod comprising: communicating using a first bandwidth part having afirst bandwidth; monitoring for control data transmitted, by the basestation, using a first control resource set for a common search space(CSS), wherein the first control resource set is conveyed in the firstbandwidth part; changing to using a second bandwidth part having asecond bandwidth for the communicating, wherein the second bandwidth isdifferent from the first bandwidth; and monitoring for control datatransmitted, by the base station, using a second control resource setfor a CSS wherein the second control resource set is conveyed in thesecond bandwidth part, wherein the second control resource set isdifferent from the first control resource set in a frequency domain, andrespective bandwidths of the first and second control resource sets areconfigured based on the respective first and second bandwidths.
 2. Themethod according to claim 1, wherein the changing is performed based onat least one of: downlink control information (DCI); an expiry of aninactive timer for a respective bandwidth part; a Media AccessControl-Control Element (MAC-CE); and a Radio Resource Control (RRC)signaling.
 3. The method according to claim 2, wherein the first controlresource set includes a control resource set for initial access, and themethod further comprises: receiving information for the control resourceset for the initial access via a Master Information Block (MIB) orsystem information.
 4. The method according to claim 2, furthercomprising: receiving information for location of one of the firstcontrol resource set and the second control resource set, and monitoringor the control data using the information for the location of the one ofthe first control resource set and the second control resource set. 5.The method according to claim 1, wherein time duration of the firstcontrol resource set and the second control resource set is at least oneof 1, 2, and 3 symbols.
 6. The method according to claim 1, wherein thechanging is performed based on the expiry of the inactive timer for arespective bandwidth part.
 7. A method performed by a base station forbandwidth adaptation for communication with a user equipment (UE), themethod comprising: communicating with the UE using a first bandwidthpart having a first bandwidth; transmitting control data, to the UE,using a first control resource set for a common search space (CSS),wherein the first control resource set is conveyed in the firstbandwidth part; changing to using a second bandwidth part having asecond bandwidth for the communicating, wherein the second bandwidth isdifferent from the first bandwidth; and transmitting control data, tothe UE, using a second control resource set for a CSS, wherein thesecond control resource set is conveyed in the second bandwidth part,wherein the second control resource set is different from the firstcontrol resource set in a frequency domain, and respective bandwidths ofthe first and second control resource sets are configured based on therespective first and second bandwidths.
 8. A user equipment (UE) forbandwidth adaptation for communication with a base station serving acommunication area, the UE comprising: a controller and a transceiver;wherein the transceiver is configured to communicate with the basestation using a first bandwidth part having a first bandwidth; andwherein the controller is configured to: monitor for control datatransmitted, by the base station, using a first control resource set fora common search space (CSS), wherein the first control resource set isconveyed in the first bandwidth part; control the transceiver to changeto using a second bandwidth part having a second bandwidth for thecommunicating, wherein the second bandwidth is different from the firstbandwidth; and monitor for control data transmitted, by the basestation, using a second control resource set for a CSS wherein thesecond control resource set is conveyed in the second bandwidth part,wherein the second control resource set is different from the firstcontrol resource set in a frequency domain, and respective bandwidths ofthe first and second control resource sets are configured based on therespective first and second bandwidths.
 9. A base station for bandwidthadaptation for communication with a user equipment (UE), the basestation comprising: a controller and a transceiver; wherein thetransceiver is configured to: communicate with the UE, using a firstbandwidth part having a first bandwidth; and transmit control data, tothe UE, using a first control resource set for a common search space(CSS), wherein the first control resource set is conveyed in the firstbandwidth part; wherein the controller is configured to control thetransceiver to change to using a second bandwidth part having a secondbandwidth for the communicating, wherein the second bandwidth isdifferent from the first bandwidth; and wherein the transceiver isconfigured to transmit control data, to the UE, using a second controlresource set for a CSS, wherein the second control resource set isconveyed in the second bandwidth part, and wherein the second controlresource set is different from the first control resource set in afrequency domain, and respective bandwidths of the first and secondcontrol resource sets are configured based on the respective first andsecond bandwidths.